Since an acrylic resin is excellent in transparency and gloss and its hardness can be freely controlled by varying the kind and amount of the constituting monomers and especially acrylic or methacrylic ester used, such a resin has been widely used in various lacquer type or baking type coating compositions as a resinous vehicle.
Particulary, an acrylic resin having as a constituting unit an end carboxyl bearing reactive acryl monomer as acrylic acid, methacrylic acid, itaconic acid or the like is known to have a curing acceleration activity in the crosslinking reaction of said resin with an aminoplast resin and therefore, it is specifically useful as a curable type resin in a paint industry.
However, in the heretofore known end carboxyl bearing reactive acryl monomers, the chain length between a vinyl group and an end carboxyl group is relatively short and therefore, when it is incorporated into an acrylic resin, thus obtained resin can exhibit only a weak curing acceleration activity and hence there often results a poor crosslinking reaction.
It is, therefore, an object of the invention to provide a novel acrylic resin which has a satisfactorily higher level of self-catalytic action in a crosslinking reaction with an aminoplast resin, capable of resulting a coating with a higher crosslink density, and which is useful as a resinous vehicle in both curable and non-curable type coating compositions. An additional object of the invention is to provide an advantageous process for the preparation of such resin.